I think using abrasive cleaners is what causes this in the first place. I used to clean my upholstery with magic earasers and/or products containing bleach whenever i would get a little bit of mold. Eventually it started looking like this and I would just up the magic eraser use. It would look good for a few days and then come back. The vinyl has a protective layer that prevents mold and mildew. I think once youv'e removed that layer the vinyl is shot. I ended up replacing the skins on my boat and now after 3 years they are still perfect. I only clean them with mild soap and use 303. If they get a little bit of mildew I leave it in the sun.